There is one VERY important observation that has been overlooked in this entire thread: In Ninja Warz, on each weapon there is a “DPS” listed and a meter showing “Speed.” Since “DPS” is actually a combination of “Damage” and “Speed,” it becomes glaringly obvious that the developers mistakenly called “Damage” “DPS.” A tested proof of this: I once received a weapon, and the game informed me that it had higher DPS. I checked, and the “DPS” was quite a bit lower. However, the “Speed” was a bit higher. I did some quick calculations assuming that they MEANT “Damage” in the “DPS” section- and sure enough, the new weapon had a higher actual DPS.
THEREFORE: To decide which weapon is better between two that you have, multiply the listed “DPS” (Damage) by the approximate “Speed” (use the marks on the meter) to get actual DPS.
NOTE: Once you know which weapon has higher DPS, be sure to consider your relics. As stated in previous posts, a slightly lower DPS weapon (fast OR slow) that synergies with your relics may be better! (I.e. A slightly lower DPS slow weapon may be better if you have a ton of critical hit relics.)